Introduction: the Role of the Orthodontist in Nutrition

Nutrition, oral health, and general health are inextricably linked. In his 2000 report on Oral Health in America, the Surgeon General of the United States emphasized the need for ‘all healthcare providers’ to play an ‘active role in promoting healthy lifestyles … by incorporating nutrition counseling into their practices’ (US Department of Health and Human Services et al., 2000). This is particularly important for dental professionals, as oral health plays an important role in nutrition and vice versa. The health of the oral cavity can facilitate or impede the desire and ability to eat. Conversely, diet and nutrition play important roles in oral health promotion and caries prevention.

The orthodontist is well positioned to help screen for dietary issues, as well as provide meaningful dietary advice. Many orthodontists report regularly engaging in dietary discussions with their patients (Huang et al., 2006). Nutrition and diet are relevant topics between practitioner and patient as good nutrition maximizes orthodontic outcomes. Orthodontists usually see patients in childhood or early adolescence. This allows for early detection of and intervention for dietary problems. When nutrition issues relate directly to dental or orthodontic issues, the orthodontist can assist in promoting behavior change for oral health. When nutrition issues are beyond the orthodontic scope of practice, referral can be made to a physician or registered dietitian.

This chapter will review the relevance of nutrition to orthodontics and how the orthodontist can assist in facilitating good nutrition for good oral health. Additionally, this chapter will provide practical advice about delivering patient education designed to promote positive dietary behavior change. A point to note before considering this in more depth is that in casual conversation the terms diet and nutrition are often used interchangeably. However, particularly in an oral health context, the difference between the two is important. Diet is the pattern of food intake, the ways in which people eat. This includes their individual food choices, the frequency of eating, and the underlying values that determine what foods are eaten or avoided. This is particularly important in dental caries etiology and prevention. Nutrition is the systemic effect of food on the body. Malnutrition can mean undernutrition, overnutrition, or nutrition that contributes to ill health such as in cardiovascular disease.

What Is an Adequate Diet?

An adequate diet is a diet that meets all of the known nutritional requirements for health. As knowledge is ever increasing about human nutritional requirements, dietary standards and guidelines are continuously updated to reflect these changes. Known human nutrient requirements are documented in the dietary reference intakes (DRIs) in the United States, and are available in table form (http://fnic.nal.usda.gov). Most countries have similar standards, however, as the standards are listed in physiologically needed amounts (e.g. grams, milligrams, micrograms/day etc.) and not in commonly consumed foods, they are not useful for educating the public. Thus, dietary guidelines and food grouping systems have been devised, as translations of the DRIs into the foods that provide them. Foods are grouped by similar nutrient content. The most recent and most comprehensive food grouping system for the United States is called MyPlate (http://www.choosemyplate.gov Figure 5.1), which not only provides the general diet guidelines for health but also provides specific recommendations based on age, gender, weight, and exercise level. Table 5.1 shows examples of the recommended daily food intake for two teenagers and two adults. The most useful approaches to diet assessment and education in dental practice compare the patient’s usual food intakes with these standards to determine general adequacy/potential concerns. The MyPlate website may be appealing for the tech-savvy adolescent age group. See Table 5.2 for a summary of the diet recommendations for adolescents and adults along with practical recommendations for meeting these guidelines.

Table 5.1 Recommended daily portions of food groups by age/gender/weight/activity

Source: US Department of Agriculture (2010).

Table 5.2 Guidelines for a healthy diet

Adapted from US Department of Health and Human Services and US Department of Agriculture, 2005. (US Department of Health and Human Services, US Department of Agriculture (2005) Dietary Guidelines for Americans, 2005. Washington DC: Government Printing Office.)

Figure 5.1 http://www.choosemyplate.gov,

(from US Department of Agriculture, 2011)

Nutrition and the Orthodontic Patient

Importance of Nutrition During Development and for Maintenance of Oral Tissues

Growth and development of all tissues and structures, including that of the oral cavity, directly depend on adequate nutrition. Tooth development begins in utero and continues until the third decade of life, when the third molars emerge into the oral cavity, and all teeth complete root formation. Following their emergence into the oral cavity the dental crowns become exposed to the oral environment. At the time of emergence, the dental roots are incomplete, and while the eruptive movement continues, the tissues surrounding the teeth model and remodel, as part of overall growth, and this activity continues in adult life. In both young people and adults, nutrition plays a pivotal role in determining the nature of tissue growth, remodeling, and the individual response to physical and chemical challenges. Thus, all age groups are dependent on consistent good nutrition (Romito, 2003).

Oral development (including tooth mineralization) begins in utero and prenatal nutrition of the mother is the first important factor that affects the ultimate oral development of the child (Tinanoff and Palmer, 2000). Maternal deficiencies of folic acid, riboflavin, and zinc during pregnancy can lead to severe craniofacial abnormalities such as cleft lip and palate in the child. General malnutrition and specific nutrient deficiencies (as well as nutrient toxicities) during tooth development can adversely affect tooth size, formation, and eruption pattern. For example, protein deficiency during early childhood can affect the tooth size and eruption sequence. Vitamin C deficiency may alter collagen formation and bone development. In developing countries where malnutrition is rampant, such nutrition-related defects are commonly observed. In developed countries, however, overt malnutrition and specific nutrient deficiencies are less common (Romito, 2003). However, issues related to nutrient toxicity do occur. A few years ago, the accidental over-fortification of milk with vitamin D by a commercial dairy resulted in malformation defects in erupted dentition in a young child (Giunta, 1998). Thus, orthodontists should be aware of the importance of nutrition during oral growth and development, and should counsel pregnant women about the importance of optimal nutrition for the wellbeing of their unborn child as well as for their own health. They should caution against the random use of nutritional supplements other than multivitamins or calcium/vitamin D supplements, unless they are prescribed by a physician.

Role of Diet in Dental Caries

The orthodontist is in an ideal position to educate patients about diet and dental caries, since orthodontic appliances increase the available surfaces for plaque accumulation, resulting in more areas for caries to occur. Following eruption, teeth are most susceptible to dental caries (2–5 years for deciduous teeth and early adolescence for permanent teeth). Caries is the result of demineralization of tooth enamel and dentin by organic acids formed by bacterial metabolism of dietary sugars. The development of dental caries is influenced primarily by the total amount of time fermentable carbohydrates (simple sugars: mono and disaccharides) are in contact with cariogenic plaque. Thus, the frequency of consumption, form of sugar (indicating retention of sugar in the mouth), and timing of consumption (at or in-between meals) are the important factors in determining caries risk. It is important to remember that the total amount of sugars consumed does not seem to be the most important factor in the cariogenic potential of the diet. Dietary patterns that include frequent snacking/ sipping on foods or beverages that contain simple sugars are more conducive to caries development than infrequent snacking (Moynihan and Petersen, 2004). Table 5.3 shows the relative cariogenicity of various foods.

Table 5.3 General cariogenic potential of different types of snack

Defining ‘Sugar’

For the general public, the term sugar that is associated with dental caries is often equated with the disaccharide sucrose, or table sugar. However, all monosaccharides (glucose, fructose, galactose) and disaccharides (sucrose, maltose, lactose) have cariogenic potential. In the realm of dental health, the term fermentable carbohydrates is often used for those carbohydrates that can be metabolized by bacteria to produce acid and as a result, increase caries risk (Kandelman, 1997). These are primarily the mono- and disaccharides, but starches can also be cariogenic when held in the mouth long enough for salivary amylase to hydrolyze them to simple sugars.

For simplicity in making recommendations to patients, it is important to communicate that protein, fats, and food fibers are not cariogenic. The only cariogenic foods are those that are composed of one or more of the simple sugars. These include sugars added during manufacturing (formerly sucrose, now primarily high-fructose corn syrup) as well as table sugar added in cooking or at the table and naturally occurring sugar found in fruit, juice, honey, and molasses (Moynihan and Petersen, 2004).

How Diet Can Help Protect the Teeth Against Caries

Saliva plays a major role in preventing dental caries by promoting enamel remineralization, cleansing the mouth, and helping neutralize acids. The act of chewing facilitates salivary flow. Many medications, including common over-the-counter ones such as antihistamines, can cause decreased salivary flow or xerostomia. Xerostomia increases the caries risk associated with the diet, due to the loss of the acid-mitigating effects. Thus hydration to maintain salivary flow is vital for caries prevention.

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